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Title: Sub-Equimolar Hydrolysis and Condensation of Organophosphates

Abstract

We characterized the in-situ hydrolysis and subsequent condensation reaction of the chemical agent simulant diethyl chlorophosphate (DECP) by high-resolution 31P NMR spectroscopy following the addition of water in sub-equimolar concentrations. Moreover, the identification and quantification of the multiple pyrophosphate and larger polyphosphate chemical species formed through a series of self-condensation reactions are reported. Finally, the DECP hydrolysis kinetics and distribution of breakdown species was strongly influenced by the water concentration and reaction temperature.

Authors:
 [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1303156
Report Number(s):
SAND2016-4563J
Journal ID: ISSN 2365-6549; 640200
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry Select
Additional Journal Information:
Journal Volume: 1; Journal Issue: 11; Journal ID: ISSN 2365-6549
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Alam, Todd M., Kinnan, Mark K., Wilson, Brendan W., and Wheeler, David R. Sub-Equimolar Hydrolysis and Condensation of Organophosphates. United States: N. p., 2016. Web. doi:10.1002/slct.201600498.
Alam, Todd M., Kinnan, Mark K., Wilson, Brendan W., & Wheeler, David R. Sub-Equimolar Hydrolysis and Condensation of Organophosphates. United States. doi:10.1002/slct.201600498.
Alam, Todd M., Kinnan, Mark K., Wilson, Brendan W., and Wheeler, David R. 2016. "Sub-Equimolar Hydrolysis and Condensation of Organophosphates". United States. doi:10.1002/slct.201600498. https://www.osti.gov/servlets/purl/1303156.
@article{osti_1303156,
title = {Sub-Equimolar Hydrolysis and Condensation of Organophosphates},
author = {Alam, Todd M. and Kinnan, Mark K. and Wilson, Brendan W. and Wheeler, David R.},
abstractNote = {We characterized the in-situ hydrolysis and subsequent condensation reaction of the chemical agent simulant diethyl chlorophosphate (DECP) by high-resolution 31P NMR spectroscopy following the addition of water in sub-equimolar concentrations. Moreover, the identification and quantification of the multiple pyrophosphate and larger polyphosphate chemical species formed through a series of self-condensation reactions are reported. Finally, the DECP hydrolysis kinetics and distribution of breakdown species was strongly influenced by the water concentration and reaction temperature.},
doi = {10.1002/slct.201600498},
journal = {Chemistry Select},
number = 11,
volume = 1,
place = {United States},
year = 2016,
month = 7
}

Journal Article:
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  • Organosilanes such as (3-mercaptopropyl)trimethoxysilane (3MPT) are used to promote a variety of desirable interfacial properties such as chemical durability, alkali resistance, electrical conduction, insulation, surface protection and adhesion. The results presented here demonstrate that Raman spectroscopy is a useful technique for evaluating molecular monolayers of organosilanes adsorbed onto metal surfaces. The data indicate that (3-mercaptopropyl)trimethoxysilane (3MPT) forms a self-assembled monolayer on silver surfaces. Upon hydrolysis, the molecules undergo a reorientation to form a Si-O-Si network across the silver surface. The Si-O-Si network contains a variety of Si-OH defects, which are similar to other silica sol-gel systems. 29 refs., 5 figs.
  • Kinetic studies of the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) during the formation of uniform silica particles were performed through determining concentrations of TEOS and silicic acid by means of gas chromatography and a conductometer, respectively. It was shown that both hydrolysis of TEOS and condensation of Si(OH){sub 4} are first order with TEOS and Si(OH){sub 4}, respectively, and the relationships of the hydrolysis and condensation rate constants with reaction condition variables, such as temperature, NH{sub 3} concentration, and H{sub 2}O concentration, were determined. in addition, the particle growth rate was investigated with relation to the hydrolysis and condensationmore » kinetics. Experiments showed that, during most of the reaction, the amount of formed particles is less than that of consumed TEOS, indicating that reaction intermediates exist during the process of silica formation. In the early stages of the Stoeber process, the reaction intermediates include silicic acid and subparticles, while in the case of seed growth experiments without the formation of new particles or after the early stages of Stoeber process, the reaction intermediates primarily consist of silicic acid and the growth rate of silica equals the rate of silicic acid condensation.« less
  • Self-assembled monolayer films of (3-mercaptopropyl)trimethoxysilane (3MPT) and their hydrolysis products on Ag and Au surfaces are characterized using Raman spectroscopy, FTIR spectroscopy, ellipsometry, X-ray photoelectron spectroscopy (XPS), and electrochemistry. 3MPT monolayers are formed through metal-thiolate bonding through the S atom on both metals, similar to other alkanethiol chemisorption chemistries. The orientation of 3MPT molecules in these monolayers is similar on both metals. Prior to hydrolysis, the molecules form an organized monolayer with the methoxy headgroups oriented largely parallel to the surface and the propyl chain in a largely trans conformation. When the methoxy groups are hydrolyzed, the 3MPT molecules cross-linkmore » through the formation of siloxane bonds. Although the surface vibrational spectroscopy indicates the presence of a small number of unreacted silanol groups on the siloxane surface, cyclic voltammetry of underpotential deposition of Pb suggests that the Si-O-Si network is highly cross-linked and relatively free from gross defects. The number of these unreacted silanols is estimated using XPS to be fewer than 5% of the original Si-O sites in the 3MPT monolayer. 72 refs., 12 figs., 3 tabs.« less